Barack Obama has said he could not hold back tears after dropping off his daughter Malia at university.
"It was a little bit like open-heart surgery," the former president said of the moment he took Malia, his eldest daughter, to Harvard University.
"I was proud that I did not cry in front of her," Mr Obama said.
"But on the way back, the Secret Service was off, looking straight ahead, pretending they weren't hearing me as I sniffled and blew my nose."
"It was rough," he added.
Mr Obama described the moment on Monday at an event for the Beau Biden Foundation. The non-profit was set up in honour of the late son of his former vice-president, Joe Biden.
"At the end of our lives, whatever else we've accomplished, the things that we'll remember are the joys that our children - and hopefully way later, our grandchildren - bring us," Mr Obama said.
Malia, 19, opted to attend Harvard having taken a year gap after high school.
Mr Obama has often talked about the importance of fatherhood to him.
"Of all the things I have done, I am most proud to be your dad," he told his daughters in his presidential farewell speech.
Mr Obama's other daughter, Sasha, 16, is still in high school and lives with her parents in their new house in Washington DC.